Random number generator

ABSTRACT

Provided is a random number generator including a single-photon emitter configured to emit single photons by pumping, a waveguide configured to guide the single photons emitted from the single-photon emitter to the inside of the waveguide, the waveguide including a first output terminal and a second output terminal that are respectively provided at both end portions of the waveguide, the single photons being output from the first output terminal and the second output terminal, and a first single-photon detector and a second single-photon detector respectively provided at the first output terminal and the second output terminal and configured to detect the single photons output from the first output terminal and the second output terminal, respectively.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from Korean Patent Application No.10-2018-0173082, filed on Dec. 28, 2018 in the Korean IntellectualProperty Office, the disclosure of which is incorporated herein in itsentirety by reference.

BACKGROUND 1. Field

Example embodiments of the present disclosure relate to random numbergenerators, and more particularly, to random number generators which maybe implemented in a compact on-chip.

2. Description of the Related Art

Random numbers refer to numbers that do not have a specified order orrule and thus are difficult to predict. A random number is used in thefields of computer science, engineering, information security, etc. Inparticular, the random number may be useful for security authenticationin the fields of financial services or telecommunication.

A conventional random number generator generates a random number byusing a mathematical algorithm. However, it is a problem that the randomnumber generated by the conventional random number generator can bepredicted by a pseudo random number. Recently, a quantum random numbergenerator, which may generate an unpredictable true random number byusing a quantum mechanical principle, is being studied.

SUMMARY

One or more example embodiments provide random number generators whichmay be implemented in a compact on-chip.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of example embodiments.

According to an aspect of an example embodiment, there is provided arandom number generator including a single-photon emitter configured toemit single photons by pumping, a waveguide configured to guide thesingle photons emitted from the single-photon emitter to the inside ofthe waveguide, the waveguide including a first output terminal and asecond output terminal that are respectively provided at both endportions of the waveguide, the single photons being output from thefirst output terminal and the second output terminal, and a firstsingle-photon detector and a second single-photon detector respectivelyprovided at the first output terminal and the second output terminal andconfigured to detect the single photons output from the first outputterminal and the second output terminal, respectively.

Each of the single photons emitted from the single-photon emitter may berandomly output from one of the first output terminal and the secondoutput terminal.

A random number may be generated based on a signal detected by the firstsingle-photon detector and the second single-photon detector.

The single-photon emitter may be provided in the waveguide or outside ofthe waveguide.

The single photons emitted from the single-photon emitter may be formeddirectly in the waveguide.

The random number generator may further include a pumping sourceconfigured to pump the single-photon emitter.

The pumping source may include an optical pumping source configured tooptically pump the single-photon emitter or an electrical pumping sourceconfigured to electrically pump the single-photon emitter.

The optical pumping source may include a laser light source.

The laser light source may include a laser diode.

The electrical pumping source may include a plurality of electrodesconfigured to apply an electric field to the single-photon emitter.

The random number generator may further include a resonator configuredto optically amplify the single photons emitted from the single-photonemitter, the resonator being provided at the waveguide.

The single-photon emitter, the waveguide, the first single-photondetector, and the second single-photon detector may be provided on asubstrate.

The substrate may include a semiconductor substrate.

The single-photon emitter may include a quantum dot.

The waveguide may include silicon or silicon oxide.

The first single-photon detector and the second single-photon detectorrespectively may include one of semiconductor detector, charge-coupleddevice, and photomultiplier tube detector.

According to an aspect of an example embodiment, there is provided arandom number generator including a pumping source, a single-photonemitter configured to emit single photons by pumping of the pumpingsource, a waveguide configured to guide the single photons emitted fromthe single-photon emitter to the inside of the waveguide, the waveguideincluding a first output terminal and a second output terminal that arerespectively provided at both end portions of the waveguide, the singlephotons being output from the first output terminal and the secondoutput terminal, and a first single-photon detector and a secondsingle-photon detector provided at the first output terminal and thesecond output terminal, respectively, and configured to detect thesingle-photons output from the first output terminal and the secondoutput terminal, respectively.

The pumping source, the single-photon emitter, the waveguide, the firstsingle-photon detector, and the second single-photon detectors may beprovided on a substrate.

The pumping source may include an optical pumping source configured tooptically pump the single-photon emitter or an electrical pumping sourceconfigured to electrically pump the single-photon emitter.

The single-photon emitter may be provided in the waveguide or outside ofthe waveguide.

The single-photon emitter may further include a quantum dot.

The random number generator may further include a resonator configuredto optically amplify the single photons emitted from the single-photonemitter, the resonator being provided in the waveguide.

According to an aspect of an example embodiment, there is provided arandom number generator including a light source configured to emitlight, a single-photon emitter including a quantum dot and configured toemit single photons based on the quantum dot being irradiated by thelight emitted from the light source, a waveguide configured to guide thesingle photons emitted from the single-photon emitter toward one of afirst output terminal and a second output terminal that are respectivelyprovided at both end portions of the waveguide, the single photons beingoutput from the first output terminal and the second output terminal,and a first single-photon detector and a second single-photon detectorprovided at the first output terminal and the second output terminal,respectively, and configured to detect the single-photons output fromthe first output terminal and the second output terminal, respectively.

The single-photon emitter, the waveguide, the first single-photondetector, and the second single-photon detector may be provided on asubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and/or other aspects will become apparent and more readilyappreciated from the following description of example embodiments, takenin conjunction with the accompanying drawings in which:

FIG. 1 is a perspective view of a random number generator according toan example embodiment;

FIG. 2 is a cross-sectional view taken along line I-I′ of FIG. 1;

FIG. 3 is a perspective view of a random number generator according toan example embodiment;

FIG. 4 is a perspective view of a random number generator according toan example embodiment;

FIG. 5 is a perspective view of a random number generator according toan example embodiment;

FIG. 6 is a perspective view of a random number generator according toan example embodiment;

FIG. 7 is a perspective view of a random number generator according toan example embodiment;

FIG. 8 is a perspective view of a random number generator according toan example embodiment; and

FIG. 9 is a perspective view of a random number generator according toan example embodiment.

DETAILED DESCRIPTION

Reference will now be made in detail to example embodiments of which areillustrated in the accompanying drawings, wherein like referencenumerals refer to like elements throughout. The thickness or size ofeach layer illustrated in the drawings may be exaggerated forconvenience of explanation and clarity. In this regard, the exampleembodiments may have different forms and should not be construed asbeing limited to the descriptions set forth herein.

Hereinafter, when a constituent element is disposed “above” or “on” toanother constituent element, the constituent element may be onlydirectly on the other constituent element or above the other constituentelements in a non-contact manner. Also, terms such as “comprise” and/or“comprising” may be construed to denote a constituent element, but maynot be construed to exclude the existence of or a possibility ofaddition of another constituent element.

The use of the terms “a” and “an” and “the” and similar referents in thecontext of describing the disclosure are to be construed to cover boththe singular and the plural. Also, the steps of all methods describedherein can be performed in any suitable order unless otherwise indicatedherein or otherwise clearly contradicted by context. The presentdisclosure is not limited to the described order of the steps. The useof any and all examples, or language provided herein, is intended merelyto better illuminate the disclosure and does not pose a limitation onthe scope of the disclosure unless otherwise claimed.

FIG. 1 is a perspective view of a random number generator 100 accordingto an example embodiment. FIG. 2 is a cross-sectional view taken alongline I-I′ of FIG. 1.

Referring to FIGS. 1 and 2, the random number generator 100 may includea single-photon emitter 130, a waveguide 140, and a first single-photondetector 151 and a second single-photon detector 152. The single-photonemitter 130 is provided in the waveguide 140, and the firstsingle-photon detector 151 and the second single-photon detector 152 areprovided respectively at both ends of the waveguide 140.

The single-photon emitter 130, the waveguide 140, and the firstsingle-photon detector 151 and the second single-photon detector 152 maybe provided on a substrate 110. A semiconductor substrate such as asilicon substrate may be used as the substrate 110. However, exampleembodiments are not limited thereto.

The single-photon emitter 130 may emit single photons P as illustratedin FIG. 2 by optical pumping. An optical pumping source for emittinglight to the single-photon emitter 130 may be provided on the substrate110. The optical pumping source may include, for example, a laser lightsource 120 for emitting laser light L.

The laser light source 120 may allow the single-photon emitter 130 toemit the single photons P by radiating the laser light L to thesingle-photon emitter 130 provided in the waveguide 140. For example, alaser diode may be used as the laser light source 120, but exampleembodiments are not limited thereto. The laser light source 120 mayemit, for example, the laser light L of a pulse type. However, exampleembodiments are not limited thereto, and laser light source may emitlaser light L of a continuous waveform.

The single-photon emitter 130 may sequentially emit the single photons Pby the irradiation of the laser light L emitted from the laser lightsource 120. The single-photon emitter 130 may include, for example, aquantum dot (QD). A quantum dot is a semiconductor particle having asize of about several nanometers and may include, for example, cadmiumselenide (CdSe), cadmium sulfide (CdS), lead selenide (PbSe), leadsulfide (PbS), indium arsenide (InAs), indium phosphide (InP), orcadmium selenide sulfide (CdSeS). However, this is merely exemplary andthe quantum dot may include various other semiconductor materials. Thequantum dot may have, for example, a core-shell structure, but exampleembodiments are not limited thereto.

When the laser light L emitted from the laser light source 120 isirradiated to the quantum dot, the quantum dot is excited and thenreturned to the original state. During the excitation of the quantumdot, the single photons P having specific energy may be sequentiallyemitted.

The single photons P emitted from the single-photon emitter 130 may beformed in the waveguide 140. In detail, the single photons P emittedfrom the single-photon emitter 130 may be formed directly in thewaveguide 140 without a separate coupling process.

The waveguide 140 may guide the progression of the single photons Pemitted from the single-photon emitter 130. When the substrate 110includes, for example, silicon, the waveguide 140 may include, forexample, silicon or silicon oxide. However, this is merely exemplaryand, in addition thereto, the waveguide 140 may include variousmaterials capable of guiding the progression of the photons P.

A first output terminal 141 and a second output terminal 142, from whichthe single photons P emitted from the single-photon emitter 130 areoutput, are respectively provided at both end portions of the waveguide140.

As illustrated in FIG. 2, each of the single photons P emitted from thesingle-photon emitter 130 may be output by randomly traveling in any oneof a direction toward the first output terminal 141 of the waveguide140, for example, in a −x-axis direction, and a direction toward thesecond output terminal 142 of the waveguide 140, for example, in a+x-axis direction. For example, as the probability that each of thesingle photons P in the waveguide 140 travels either in the directiontoward the first output terminal 141, that is, the −x-axis direction, orin the direction toward the second output terminal 142, that is, the+x-axis direction, is 50% due to unbiasedness of the waveguide 140,whether each of the photons P of the waveguide 140 travels in thedirection toward the first output terminal 141 or in the directiontoward the second output terminal 142 may not be predicted.

The first single-photon detector 151 and the second single-photondetector 152 for detecting the single photons P are provided at thefirst output terminal 141 and the second output terminal 142,respectively. The first single-photon detector 151 may detect the singlephotons P output from the first output terminal 141 of the waveguide140, and the second single-photon detector 152 may detect the singlephotons P output from the second output terminal 142 of the waveguide140. Each of the first single-photon detector 151 and the secondsingle-photon detector 152 may include, for example, a semiconductordetector, a charge-coupled device (CCD), or a photomultiplier tubedetector. However, example embodiments are not limited thereto.

In the random number generator 100 according to an example embodiment,when the laser light L emitted from the laser light source 120 isirradiated to the single-photon emitter 130 provided in the waveguide140, the single-photon emitter 130 sequentially emits the single photonsP due to the optical pumping by the laser light source 120. Next, eachof the single photons P emitted from the single-photon emitter 130travels inside the waveguide 140 to be randomly output either in thedirection toward the first output terminal 141 or in the directiontoward the second output terminal 142. Next, the first single-photondetector 151 and the second single-photon detector 152 detect the singlephotons P output from the first output terminal 141 and the secondoutput terminal 142, respectively.

As the single photons P are detected by the first single-photon detector151 and the second single-photon detector 152, a random number may begenerated. For example, when one single photon P emitted from thesingle-photon emitter 130 is output from the first output terminal 141of the waveguide 140 and detected by the first single-photon detector151, “0” may be set, and when the other single photon P emitted from thesingle-photon emitter 130 is output from the second output terminal 142of the waveguide 140 and detected by the second single-photon detector152, “1” may be set. A setting opposite to the above may be performed.

As such, one (1) bit may be determined according to whether each of thesingle photons P emitted from the single-photon emitter 130 is outputfrom the first output terminal 141 or from the second output terminal142. Accordingly, an unpredictable true random number may be generatedby the single photons P that are sequentially emitted from thesingle-photon emitter 130.

A random number generator using quantum mechanical amorphousness ofphotons has been studied. However, the random number generator requiresoptical elements such as a polarized plate or mirror so thatminiaturization of the random number generator may be difficult andcosts may be increased. According to example embodiments, as allconstituent elements such as the laser light source 120, thesingle-photon emitter 130, the waveguide 140, and the firstsingle-photon detector 151 and the second single-photon detector 152 maybe integrated on the substrate 110, the random number generator 100 maybe implemented in a compact on-chip at a relatively low cost.Furthermore, an unpredictable true random number may be generated byusing a quantum mechanical principle.

FIG. 3 is a perspective view of a random number generator 200 accordingto an example embodiment. The following description mainly focuses ondifferences from the above-described example embodiment.

Referring to FIG. 3, the random number generator 200 may include a laserlight source 220, a single-photon emitter 230, a waveguide 240, aresonator 270, and a first single-photon detector 251 and a secondsingle-photon detector 252. The laser light source 220, thesingle-photon emitter 230, the waveguide 240, the resonator 270, and thefirst single-photon detector 251 and the second single-photon detector252 may be provided on a substrate 210.

In the example embodiment, the resonator 270 for optical amplificationis provided in the waveguide 240, and the single-photon emitter 230 isprovided in the resonator 270. The first single-photon detector 251 andthe second single-photon detector 252 are respectively provided at bothend portions of the waveguide 240.

The laser light source 220, as an optical pumping source, radiates thelaser light L to the single-photon emitter 230 so that single photonsmay be emitted from the single-photon emitter 230. A laser diode, forexample, may be used as the laser light source 220, but exampleembodiments are not limited thereto. The laser light source 220 mayemit, for example, the laser light L of a pulse type or the laser lightL of a continuous waveform.

The single-photon emitter 230 may sequentially emit the single photonsby the irradiation of the laser light L emitted from the laser lightsource 220. The single-photon emitter 230 may include, for example, aquantum dot, but example embodiments are not limited thereto.

The single-photon emitter 230 may be provided in the resonator 270.Accordingly, the single photons emitted from the single-photon emitter230 may be formed in the resonator 270 by the irradiation of the laserlight L emitted from the laser light source 220. The resonator 270 mayamplify the light generated from the single-photon emitter 230 by usinga mirror structure provided therein and output the amplified lighttoward the waveguide 240.

The waveguide 240 may guide the progression of the single photonsgenerated by the single-photon emitter 230 and amplified by theresonator 270. A first output terminal 241 and a second output terminal242 for outputting single photons are respectively provided at both endportions of the waveguide 240. The first single-photon detector 251 andthe second single-photon detector 252 for detecting photons are providedat the first output terminal 241 and the second output terminal 242,respectively. The first single-photon detector 251 may detect the singlephotons output from the first output terminal 241 of the waveguide 240,and the second single-photon detector 252 may detect the single photonsoutput from the second output terminal 242 of the waveguide 240.

As described above, each of the single photons emitted from thesingle-photon emitter 230 is amplified by the resonator 270 and thenrandomly travels to be output in any one of a direction toward the firstoutput terminal 241 of the waveguide 240 and a direction toward thesecond output terminal 242 of the waveguide 240. As the randomly outputsingle photons are detected by the first single-photon detector 251 andthe second single-photon detector 252, a random number may be generated.

According to the example embodiment, in the random number generator 200,as the resonator 270 for optical amplification is provided in thewaveguide 240, pumping efficiency may be improved. Accordingly,single-photon detection efficiency may be improved.

FIG. 4 is a perspective view of a random number generator 300 accordingto an example embodiment.

Referring to FIG. 4, the random number generator 300 may include a laserlight source 320, a single-photon emitter 330, a waveguide 340, and afirst single-photon detector 351 and a second single-photon detector352. The laser light source 320, the single-photon emitter 330, thewaveguide 340, and the first single-photon detector 351 and the secondsingle-photon detector 352 may be provided on a substrate 310. In theexample embodiment, the single-photon emitter 330 is provided outside ofthe waveguide 340, and the first single-photon detector 351 and thesecond single-photon detector 352 are respectively provided at both endportions of the waveguide 340.

The laser light source 320, as an optical pumping source, radiates thelaser light L to the single-photon emitter 330 so that the single-photonemitter 330 may emit single photons. A laser diode, for example, may beused as the laser light source 320, but example embodiments are notlimited thereto. The laser light source 320 may emit, for example, thelaser light L of a pulse type or the laser light L of a continuouswaveform.

The single-photon emitter 330 may emit the single photons by theirradiation of the laser light L emitted from the laser light source320. The single-photon emitter 330 may include, for example, a quantumdot, but example embodiments are not limited thereto. The single-photonemitter 330 may be provided outside the waveguide 340. FIG. 4illustrates an example in which the single-photon emitter 330 isprovided outside of the waveguide 340 and in contact with the waveguide340. However, example embodiments are not limited thereto, and thesingle-photon emitter 330 may be provided outside of the waveguide 340and spaced apart from the waveguide 340.

The single photons emitted from the single-photon emitter 330 may beformed in the waveguide 340. For example, the light generated from thesingle-photon emitter 330 may be input to the inside of the waveguide340 without a separate coupling device. Accordingly, the single photonsemitted from the single-photon emitter 330 may be formed directly in thewaveguide 340.

The waveguide 340 may guide the progression of the single photonsemitted from the single-photon emitter 330. A first output terminal 341and a second output terminal 342 for outputting the single photonsemitted from the single-photon emitter 330 are respectively provided atboth end portions of the waveguide 340.

The first single-photon detector 351 and the second single-photondetector 352 for detecting the single photons are provided at the firstoutput terminal 341 and the second output terminal 342, respectively.The first single-photon detector 351 may detect the single photonsoutput from the first output terminal 341 of the waveguide 340, and thesecond single-photon detector 352 may detect the single photons outputfrom the second output terminal 342 of the waveguide 340.

As described above, each of the single photons emitted from thesingle-photon emitter 330 may be output by randomly traveling in any oneof a direction toward the first output terminal 341 of the waveguide 340and a direction toward the second output terminal 342 of the waveguide340. As the randomly output single photons are detected by the firstsingle-photon detector 351 and the second single-photon detector 352, arandom number may be generated.

FIG. 5 is a perspective view of a random number generator 400 accordingto an example embodiment.

Referring to FIG. 5, the random number generator 400 may include a laserlight source 420, a single-photon emitter 430, a waveguide 440, aresonator 470, and a first single-photon detector 451 and a secondsingle-photon detector 452. The laser light source 420, thesingle-photon emitter 430, the waveguide 440, the resonator 470, and thesingle-photon detector 451 and the second single-photon detector 452 maybe provided on a substrate 410.

In the example embodiment, the resonator 470 is provided in waveguide440, and the single-photon emitter 430 is provided outside the resonator470. The first single-photon detector 451 and the second single-photondetector 452 are respectively provided at both end portions of thewaveguide 440.

The laser light source 420, as an optical pumping source, radiates thelaser light L to the single-photon emitter 430 so that the single-photonemitter 430 may emit single photons. A laser diode, for example, may beused as the laser light source 420, but example embodiments are notlimited thereto.

The single-photon emitter 430 may emit the single photons by theirradiation of the laser light L emitted from the laser light source420. The single-photon emitter 430 may include, for example, a quantumdot, but example embodiments are not limited thereto. The single-photonemitter 430 may be provided outside the resonator 470. Although FIG. 5illustrates that the single-photon emitter 430 is provided outside ofand in contact with the resonator 470, the single-photon emitter 430 maybe provided outside of the resonator 470 and spaced apart from theresonator 470.

The single photons emitted from the single-photon emitter 430 may beformed in the resonator 440. In detail, the light generated by thesingle-photon emitter 430 may be input to the inside of the resonator470 without a separate coupling device. Accordingly, the single photonsemitted from the single-photon emitter 430 may be formed directly in theresonator 470.

The resonator 470 may output the light by amplifying the light using amirror structure, and may amplify the light generated from thesingle-photon emitter 430 and output the amplified light toward thewaveguide 440. Accordingly, the single-photon detection efficiency maybe improved.

The waveguide 440 may guide the progression of the single photonsemitted by the single-photon emitter 430 and amplified by the resonator470. A first output terminal 441 and a second output terminal 442 foremitting the single photons are respectively provided at both endportions of the waveguide 440. The first single-photon detector 451 andthe second single-photon detector 452 for detecting the single photonsare provided at the first output terminal 441 and the second outputterminal 442, respectively. The first single-photon detector 451 maydetect the single photons output from the first output terminal 441 ofthe waveguide 440, and the second single-photon detector 452 may detectthe single photons output from the second output terminal 442 of thewaveguide 440.

As described above, each of the single photons emitted from thesingle-photon emitter 430 is amplified by the resonator 470 and then maybe output by randomly traveling in any one of a direction toward thefirst output terminal 441 of the waveguide 440 and a direction towardthe second output terminal 442 of the waveguide 440. As the randomlyoutput single photons are detected by the first single-photon detector451 and the second single-photon detector 452, a random number may begenerated.

FIG. 6 is a perspective view of a random number generator 500 accordingto an example embodiment.

Referring to FIG. 6, the random number generator 500 may include asingle-photon emitter 530, a waveguide 540, and a first single-photondetector 551 and a second single-photon detector 552. The single-photonemitter 530 is provided in the waveguide 540, and the firstsingle-photon detector 551 and the second single-photon detector 552 arerespectively provided at both end portions of the waveguide 540,respectively.

The single-photon emitter 530, the waveguide 540, and the firstsingle-photon detector 551 and the second single-photon detector 552 maybe provided on a substrate 510. A semiconductor substrate such as asilicon substrate may be used as the substrate 510. However, exampleembodiments are not limited thereto.

The single-photon emitter 530 may emit single photons by electricalpumping. An electrical pumping source may be provided on the substrate510. The electrical pumping source may include a first electrode 521 anda second electrode 522 for applying an electric field to thesingle-photon emitter 530.

As the first electrode 521 and the second electrode 522 apply anelectric field to the single-photon emitter 530 provided in thewaveguide 540, the single-photon emitter 530 may emit single photons.The first electrode 521 and the second electrode 522 may be providedoutside the waveguide 540. FIG. 6 illustrates that the first electrode521 and the second electrode 522 are provided in contact with oppositeouter surfaces of the waveguide 540 with the single-photon emitter beingprovided between the first electrode 521 and the second electrode 522,but example embodiments are not limited thereto, and the first electrode521 and the second electrode 522 may be provided outside of thewaveguide 540 and space apart from the waveguide 540.

The single-photon emitter 530 may emit the single photons by an electricfield formed by a voltage difference applied between the first electrode521 and the second electrode 522. The single-photon emitter 530 mayinclude, for example, a quantum dot. A quantum dot is a semiconductorparticle having a size of about several nanometers and may include, forexample, CdSe, CdS, PbSe, PbS, InAs, InP, or CdSeS. However, this ismerely exemplary and the quantum dot may include various othersemiconductor materials. The quantum dot may have, for example, acore-shell structure, but example embodiments are not limited thereto.

The single photons emitted from the single-photon emitter 530 may beformed in the waveguide 540. The single photons emitted from thesingle-photon emitter 530 may be formed directly in the waveguide 540without a separate coupling process.

The waveguide 540 may guide the progression of the single photonsemitted from the single-photon emitter 530. When the substrate 510includes, for example, silicon, the waveguide 540 may include, forexample, silicon or silicon oxide. However, this is merely exemplary,and the waveguide 540 may include various materials capable of guidingthe progression of the single photons. A first output terminal 541 and asecond output terminal 542 for outputting the single photons emittedfrom the single-photon emitter 530 are respectively provided at both endportions of the waveguide 540.

Each of the single photons emitted from the single-photon emitter 530may be output by randomly traveling in any one of a direction toward thefirst output terminal 541 of the waveguide 540 and a direction towardthe second output terminal 542 of the waveguide 540.

The first single-photon detectors 551 and the second single-photondetector 552 for detecting the single photons are provided at the firstoutput terminal 541 and the second output terminal 542, respectively.The first single-photon detector 551 may detect the single photonsoutput from the first output terminal 541 of the waveguide 540, and thesecond single-photon detector 552 may detect the single photons outputfrom the second output terminal 542 of the waveguide 540. Each of thefirst single-photon detectors 551 and the second single-photon detector552 may include, for example, a semiconductor detector, a CCD, or aphotomultiplier tube detector. However, example embodiments are notlimited thereto.

In the random number generator 500 configured as above, when an electricfield is applied by the first electrode 521 and the second electrode 522to the single-photon emitter 530 provided in the waveguide 540, thesingle-photon emitter 530 may emit the single photons by electricalpumping. Next, each of the single photons emitted from the single-photonemitter 530 traveling inside the waveguide 540 may randomly traveleither in the direction toward the first output terminal 541 or thedirection toward the second output terminal 542 to be output from thefirst output terminal 541 or the second output terminal 542. Next, asthe first single-photon detector 551 and the second single-photondetector 552 detect the single photons output from the first outputterminal 541 and the second output terminal 542, respectively, randomnumbers may be generated.

As such, one (1) bit may be determined according to whether each of thesingle photons emitted from the single-photon emitter 530 is output fromthe first output terminal 541 or from the second output terminal 542.Accordingly, an unpredictable true random number may be generated by thesingle photons that are sequentially emitted from the single-photonemitter 530. Furthermore, as all constituent elements forming the randomnumber generator 500 are integrated on the substrate 510, the randomnumber generator 500 may be implemented in a compact on-chip at arelatively low cost.

FIG. 7 is a perspective view of a random number generator 600 accordingto an example embodiment.

Referring to FIG. 7, the random number generator 600 may include asingle-photon emitter 630, a waveguide 640, a resonator 670, and a firstsingle-photon detector 651 and a second single-photon detector 652. Thesingle-photon emitter 630, the waveguide 640, the resonator 670, and thefirst single-photon detector 651 and the second single-photon detector652 may be provided on a substrate 610.

In the example embodiment, the resonator 670 for optical amplificationis provided in the waveguide 640. The single-photon emitter 630 isprovided in the resonator 670. The first single-photon detector 651 andthe second single-photon detector 652 are respectively provided at bothend portions of the waveguide 640.

An electrical pumping source may be provided on the substrate 610. Theelectrical pumping source may include a first electrode 621 and a secondelectrode 622 for applying an electric field to the single-photonemitter 630. As the first electrode 621 and the second electrode 622apply an electric field to the single-photon emitter 530 provided in thewaveguide 640, the single-photon emitter 630 may emit single photons.

The first electrode 621 and the second electrode 622 may be providedoutside the resonator 670. The first electrode 621 and second electrode622 may be provided outside of and in contact with an outer surface ofthe resonator 670 or provided outside of the resonator 670 and spacedapart from the resonator 670. The single-photon emitter 630 may emitsingle photons by the electric field applied by the first electrode 621and the second electrode 622. The single-photon emitter 630 may include,for example, a quantum dot, but example embodiments are not limitedthereto.

The single-photon emitter 630 is provided in the resonator 670.Accordingly, the single photons emitted from the single-photon emitter630 may be formed in the resonator 670. The resonator 670 that amplifiesand outputs light may amplify the light generated by the single-photonemitter 630 to be output toward the waveguide 640.

The waveguide 640 may guide the progression of the single photonsgenerated by the single-photon emitter 630 and amplified by theresonator 670. A first output terminal 641 and a second output terminal642, from which the single photons are output, are respectively providedat both end portions of the waveguide 640. The first single-photondetector 651 and the second single-photon detector 652 for detecting thesingle photons are provided at the first output terminal 641 and thesecond output terminal 642, respectively. The first single-photondetector 651 may detect the single photons output from the first outputterminal 641 of the waveguide 640, and the second single-photon detector652 may detect the single photons output from the second output terminal642 of the waveguide 640.

As described above, each of the single photons emitted from thesingle-photon emitter 630 is amplified by the resonator 670 and thenoutput by randomly traveling in any one of the direction toward thefirst output terminal 641 of the waveguide 640 and the direction towardthe second output terminal 642 of the waveguide 640. As the randomlyoutput single photons are detected by the first single-photon detector651 and the second single-photon detector 652, a random number may begenerated.

According to the example embodiment, in the random number generator 600,as the resonator 670 for optical amplification is provided in thewaveguide 640, pumping efficiency may be improved. Accordingly, thesingle-photon detection efficiency may be improved.

FIG. 8 is a perspective view of a random number generator 700 accordingto an example embodiment.

Referring to FIG. 8, the random number generator 700 may include asingle-photon emitter 730, a waveguide 740, and a first single-photondetector 751 and a second single-photon detector 752. The single-photonemitter 730, the waveguide 740, and the first single-photon detector 751and the second single-photon detector 752 may be provided on a substrate710. In the example embodiment, the single-photon emitter 730 isprovided outside the waveguide 740, and the first single-photon detector751 and the second single-photon detector 752 are respectively providedat both end portions of the waveguide 740.

An electrical pumping source may be provided on the substrate 710. Theelectrical pumping source may include a first electrode 721 and a secondelectrode 722 for applying an electric field to the single-photonemitter 730. As the first electrode 721 and the second electrode 722apply an electric field to the single-photon emitter 730 providedoutside the waveguide 740, the single-photon emitter 730 may emit singlephotons.

The single-photon emitter 730 may include, for example, a quantum dotthat emits single photons by the application of an electric field.However, example embodiments are not limited thereto. The single-photonemitter 730 may be provided outside of and in contact with the waveguide740 or outside of the waveguide 740 and spaced apart from the waveguide740.

The first electrode 721 and the second electrode 722 may be provided atboth end portions of the single-photon emitter 730. FIG. 8 illustratesthat the first electrode 721 and the second electrode 722 are providedin contact with the single-photon emitter 730. However, this is merelyexemplary, and the first electrode 721 and the second electrode 722 maybe provided outside the single-photon emitter 730 and spaced apart fromthe single-photon emitter 730.

The single photons emitted from the single-photon emitter 730 may beformed in the waveguide 740. For example, the light generated by thesingle-photon emitter 730 may be input to the inside of the waveguide740 without a separate coupling device. Accordingly, the single photonsemitted from the single-photon emitter 730 may be formed directly in thewaveguide 740.

The waveguide 740 may guide the progression of the single photonsemitted from the single-photon emitter 730. A first output terminal 741and a second output terminal 742, from which the single photons emittedfrom the single-photon emitter 730 are output, are respectively providedat both end portions of the waveguide 740.

The first single-photon detector 751 and the second single-photondetector 752 for detecting the single photons are provided at the firstoutput terminal 741 and the second output terminal 742, respectively.The first single-photon detector 751 may detect the single photonsoutput from the first output terminal 741 of the waveguide 740, and thesecond single-photon detector 752 may detect the single photons outputfrom the second output terminal 742 of the waveguide 740.

Each of the single photons emitted from the single-photon emitter 730may be output by randomly traveling in any one of a direction toward thefirst output terminal 741 of the waveguide 740 and a direction towardthe second output terminal 742 of the waveguide 740. As the randomlyoutput single photons are detected by the first single-photon detector751 and the second single-photon detector 752, a random number may begenerated.

FIG. 9 is a perspective view of a random number generator 800 accordingto an example embodiment.

Referring to FIG. 9, the random number generator 800 may include asingle-photon emitter 830, a waveguide 840, a resonator 870, and a firstsingle-photon detector 851 and a second single-photon detector 852. Thesingle-photon emitter 830, the waveguide 840, the resonator 870, and thefirst single-photon detector 851 and the second single-photon detector852 may be provided on a substrate 810. In the example embodiment, theresonator 870 is provided in the waveguide 840, and the single-photonemitter 830 is provided outside of the resonator 870. The firstsingle-photon detector 851 and the second single-photon detector 852 arerespectively provided at both end portions of the waveguide 840.

An electrical pumping source may be provided on the substrate 810. Theelectrical pumping source may include a first electrode 821 and a secondelectrode 822 for applying an electric field to the single-photonemitter 830. As the first electrode 821 and the second electrode 822apply an electric field to the single-photon emitter 830 providedoutside of the resonator 870, the single-photon emitter 830 may emitsingle photons.

The single-photon emitter 830 may include, for example, a quantum dotthat emits single photons by the application of an electric field.However, example embodiments are not limited thereto. The single-photonemitter 830 may be provided outside of and in contact with the resonator870 or outside of the resonator 870 and spaced apart from the resonator870.

The first electrode 821 and the second electrode 822 may be provided atboth sides of the single-photon emitter 830. The first electrode 821 andthe second electrode 822 may be provided in contact with thesingle-photon emitter 830 or around the single-photon emitter 830 to beapart from the single-photon emitter 830.

The photons emitted from the single-photon emitter 830 may be formed inthe resonator 870. For example, the light generated by the single-photonemitter 830 may be input to the inside of the resonator 870 without aseparate coupling device, Accordingly, the single photons emitted fromthe single-photon emitter 830 may be formed directly in the resonator870. As the resonator 870 may amplify the light generated by thesingle-photon emitter 830 and output the amplified light toward thewaveguide 840, the single-photon detection efficiency may be improved.

The waveguide 840 may guide the progression of the single photonsemitted by the single-photon emitter 830 and amplified by the resonator870. A first output terminal 841 and a second output terminal 842 foremitting the single photons are respectively provided at both endportions of the waveguide 840. The first single-photon detector 851 andthe second single-photon detector 852 for detecting the single photonsare provided at the first output terminal 841 and the second outputterminal 842, respectively. The first single-photon detector 851 maydetect the single photons output from the first output terminal 841 ofthe waveguide 840, and the second single-photon detector 852 may detectthe single photons output from the second output terminal 842 of thewaveguide 840.

Each of the single photons emitted from the single-photon emitter 830 isamplified by the resonator 870 and may be output by randomly travelingin any one of a direction toward the first output terminal 841 of thewaveguide 840 and a direction toward the second output terminal 842 ofthe waveguide 840. As the randomly output single photons are detected bythe first single-photon detector 851 and the second single-photondetector 852, a random number may be generated.

According to the example embodiments, since all constituent elementssuch as a pumping source, a single-photon emitter, a waveguide, asingle-photon detector, etc. may be integrated on a substrate, a randomnumber generator may be implemented in a compact on-chip type at arelatively low cost. Furthermore, unpredictable true random numbers maybe generated by using a quantum mechanical principle.

It should be understood that example embodiments described herein shouldbe considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments.

While example embodiments have been described with reference to thefigures, it will be understood by those of ordinary skill in the artthat various changes in form and details may be made therein withoutdeparting from the spirit and scope as defined by the following claims.

What is claimed is:
 1. A random number generator comprising: asingle-photon emitter configured to emit single photons by pumping; awaveguide configured to guide the single photons emitted from thesingle-photon emitter to the inside of the waveguide, the waveguidecomprising a first output terminal and a second output terminal that arerespectively provided at both end portions of the waveguide, the singlephotons being output from the first output terminal and the secondoutput terminal; and a first single-photon detector and a secondsingle-photon detector respectively provided at the first outputterminal and the second output terminal and configured to detect thesingle photons output from the first output terminal and the secondoutput terminal, respectively.
 2. The random number generator of claim1, wherein each of the single photons emitted from the single-photonemitter is randomly output from one of the first output terminal and thesecond output terminal.
 3. The random number generator of claim 2,wherein a random number is generated based on a signal detected by thefirst single-photon detector and the second single-photon detector. 4.The random number generator of claim 2, wherein the single-photonemitter is provided in the waveguide or outside of the waveguide.
 5. Therandom number generator of claim 4, wherein the single photons emittedfrom the single-photon emitter are formed directly in the waveguide. 6.The random number generator of claim 1, further comprising a pumpingsource configured to pump the single-photon emitter.
 7. The randomnumber generator of claim 6, wherein the pumping source comprises anoptical pumping source configured to optically pump the single-photonemitter or an electrical pumping source configured to electrically pumpthe single-photon emitter.
 8. The random number generator of claim 7,wherein the optical pumping source comprises a laser light source. 9.The random number generator of claim 8, wherein the laser light sourcecomprises a laser diode.
 10. The random number generator of claim 7,wherein the electrical pumping source comprises a plurality ofelectrodes configured to apply an electric field to the single-photonemitter.
 11. The random number generator of claim 1, further comprisinga resonator configured to optically amplify the single photons emittedfrom the single-photon emitter, the resonator being provided at thewaveguide.
 12. The random number generator of claim 1, wherein thesingle-photon emitter, the waveguide, the first single-photon detector,and the second single-photon detector are provided on a substrate. 13.The random number generator of claim 12, wherein the substrate comprisesa semiconductor substrate.
 14. The random number generator of claim 1,wherein the single-photon emitter comprises a quantum dot.
 15. Therandom number generator of claim 1, wherein the waveguide comprisessilicon or silicon oxide.
 16. The random number generator of claim 1,wherein the first single-photon detector and the second single-photondetector respectively comprise one of semiconductor detector,charge-coupled device, and photomultiplier tube detector.
 17. A randomnumber generator comprising: a pumping source; a single-photon emitterconfigured to emit single photons by pumping of the pumping source; awaveguide configured to guide the single photons emitted from thesingle-photon emitter to the inside of the waveguide, the waveguidecomprising a first output terminal and a second output terminal that arerespectively provided at both end portions of the waveguide, the singlephotons being output from the first output terminal and the secondoutput terminal; and a first single-photon detector and a secondsingle-photon detector provided at the first output terminal and thesecond output terminal, respectively, and configured to detect thesingle-photons output from the first output terminal and the secondoutput terminal, respectively.
 18. The random number generator of claim17, wherein the pumping source, the single-photon emitter, thewaveguide, the first single-photon detector, and the secondsingle-photon detectors are provided on a substrate.
 19. The randomnumber generator of claim 17, wherein the pumping source comprises anoptical pumping source configured to optically pump the single-photonemitter or an electrical pumping source configured to electrically pumpthe single-photon emitter.
 20. The random number generator of claim 17,wherein the single-photon emitter is provided in the waveguide oroutside of the waveguide.
 21. The random number generator of claim 17,wherein the single-photon emitter further comprises a quantum dot. 22.The random number generator of claim 17, further comprising a resonatorconfigured to optically amplify the single photons emitted from thesingle-photon emitter, the resonator being provided in the waveguide.23. A random number generator comprising: a light source configured toemit light; a single-photon emitter comprising a quantum dot andconfigured to emit single photons based on the quantum dot beingirradiated by the light emitted from the light source; a waveguideconfigured to guide the single photons emitted from the single-photonemitter toward one of a first output terminal and a second outputterminal that are respectively provided at both end portions of thewaveguide, the single photons being output from the first outputterminal and the second output terminal; and a first single-photondetector and a second single-photon detector provided at the firstoutput terminal and the second output terminal, respectively, andconfigured to detect the single-photons output from the first outputterminal and the second output terminal, respectively.
 24. The randomnumber generator of claim 23, wherein the single-photon emitter, thewaveguide, the first single-photon detector, and the secondsingle-photon detector are provided on a substrate.